The present invention relates to a method for producing an olefin type copolymer having a cyclic structure. More particularly, the present invention relates to a method which comprises copolymerizing ethylene and dicyclopentadiene or tricyclopentadiene, and, as optionally introduced, a cyclic olefin, in the presence of a catalyst system comprising a metallocene compound and an aluminoxane, whereby an olefin type copolymer having a cyclic structure, which has a high content of dicyclopentadiene or tricyclopentadiene, or a cyclic olefin, and which has a narrow molecular weight distribution, can be produced efficiently with a high catalytic activity.
An olefin type addition polymer having a cyclic structure obtainable by copolymerization of an xcex1-olefin with a cyclic olefin represented by 2-norbornene, or a so-called cyclic polyene containing at least two double bonds in its molecule (hereinafter sometimes referred to simply as a cyclic structure-containing copolymer), usually has a high glass transition temperature or high transparency as compared with an olefin type polymer containing no cyclic structure, and accordingly, it is expected to be useful for various molded products including optical materials. Various methods have been known for the production of such a ring structure-containing copolymer. With respect to a copolymer of an xcex1-olefin with norbornene and its derivatives, or a cyclic olefin such as a cyclopentadiene derivative, for example, JP-A-60-168708 or JP-A-61-271308 discloses a method of using a catalyst comprising a vanadium compound and an organic aluminum compound. However, such a method had a problem that the catalytic activity was low. As methods to have such a problem overcome, JP-A-61-221206, JP-A-64-106 and JP-A-2-173112 disclose methods of using catalysts comprising various metallocene compounds and aluminoxanes. These methods are improved from the viewpoint that the catalytic activities are relatively high, and good catalytic efficiency can be accomplished. However, the efficiency for copolymerization of the cyclic olefin to the xcex1-olefin is inadequate. Accordingly, it is desired to have the polymerization activities further improved or to have the efficiency for copolymerization of the cyclic olefin and the cyclic polyene to the xcex1-olefin improved.
On the other hand, a method for producing a cyclic structure-containing copolymer by copolymerizing an xcex1-olefin with a cyclic polyene as dicyclopentadiene or its derivative, is also known. For example, JP-A-63-243103 or JP-A-63-314220 discloses a method of employing a catalyst comprising a vanadium compound and an organic aluminum compound, and JP-A-7-70250 discloses a method of using a catalyst comprising a metallocene compound and an aluminoxane. However, these methods also had a problem that not only the catalytic activities were low, but also the efficiency for copolymerization of a cyclic polyene such as dicyclopentadiene to the xcex1-olefin was low. Thus, an industrially adequately satisfactory method has not yet been found for the production of an olefin type copolymer having a cyclic structure.
A cyclic polyene such as dicyclopentadiene or tricyclopentadiene to be used in the present invention, has two isomers i.e. an exoform isomer and an endoform isomer, and the proportion of the endoform isomer is predominant, which has a five-membered ring constituting a stereostructure closer to the ring containing a double bond to be involved in polymerization. Such a close five-membered ring constitutes a steric hindrance, whereby polymerization tends to be difficult. Further, it is known that a copolymer obtained by using, as a starting material, a cyclic polyene such as dicyclopentadiene or tricyclopentadiene, is usually susceptible to crosslinking as compared with a case where a cyclic olefin is employed, whereby a gelled polymer component is likely to be formed, and as a result, a polymer insoluble in a solvent tends to be formed. Whereas, in an application to e.g. an optical material, the uniformity of the material is important, and if such a gelled polymer component insoluble in a solvent is formed, the commercial value will be substantially impaired. Accordingly, dicyclopentadiene or tricyclopentadiene as a monomer for copolymerization, is essentially a material not preferred for the purpose of obtaining an olefin type addition polymer.
The above-mentioned gelled polymer component is likely to be formed usually when the catalytic activities are low, or when the efficiency for copolymerization of the catalyst is so poor that it is obliged to increase the charge of the cyclic polyene, or when the polymerization temperature is made high. Such a problem is attributable to an inadequate performance of the catalyst, and a catalyst having a high performance which brings about no such a problem, is desired.
Accordingly, it is an object of the present invention to provide a method whereby, even if a cyclic polyene such as dicyclopentadiene or tricyclopentadiene which is hardly copolymerizable with an xcex1-olefin, is used as a monomer material, a gelled polymer component will not be formed, the efficiency for copolymerization of a cyclic polyene and a cyclic olefin is high, polymerization activity is excellent, and still it is possible to efficiently produce an olefin type copolymer having a cyclic structure and a narrow molecular weight distribution.
The present inventors have conducted an extensive research on a method for producing an olefin type copolymer having a cyclic structure by means of a metallocene type catalyst, and as a result, have found that when a metallocene compound having a certain specific structure is combined with an aluminoxane, it is possible to solve all of the above problems and to accomplish the object of the present invention. The present invention has been accomplished on the basis of this discovery.
Namely, the present invention provides a method for producing an olefin type copolymer having a cyclic structure, which comprises copolymerizing ethylene (M1) and dicyclopentadiene or tricyclopentadiene (M2), and, as optionally introduced, a cyclic olefin (M3), wherein, as a catalyst, a catalyst comprising a metallocene compound (A) of the following formula [1]:
H2C(Rxe2x80x2mCp) (Rxe2x80x3nCp)MX2xe2x80x83xe2x80x83[1]
wherein M is zirconium or hafnium, Cp is a group having a cyclopentadienyl skeleton, each of Rxe2x80x2 and Rxe2x80x3 is a hydrocarbon group having 1 to 10 carbon atoms, each of two X""s which may be the same or different from each other, is a halogen atom, a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogenated hydrocarbon group, an alkylamino group, an alkoxy group, an aryloxy group of the formula xe2x80x94Oxe2x80x94Arxe2x80x94Yp (wherein Ar is an aromatic ring, Y is a halogen atom, a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogenated hydrocarbon group, an alkoxy group, an alkylamino group, a cyano group or a nitro group, and p is an integer of from 1 to 5), a thioalkyl group, or a thioaryl group of the formula xe2x80x94Sxe2x80x94Arxe2x80x94Yp (wherein Ar, Y and p are as defined above), and each of n and m is an integer of from 0 to 4, provided that m and n are not equal, and m+n is an integer of from 3 to 6, and an aluminoxane (B), is used.
In the present invention, a specifically good result is obtained when the metallocene compound (A) is a compound wherein two cyclopentadiene rings bonded to the transition metal atom are different (asymmetric) and the two cyclopentadiene rings are bonded by a methylene group.
Now, the present invention will be described in further detail with reference to the preferred embodiments.
Among the monomer components (M2) to be used in the present invention, dicyclopentadiene is called also as 3a,4,7,7a-tetrahydro-4,7-methanoindene and is obtainable in a relatively large amount from the decomposition components of naphtha. Among the components (M2), tricyclopentadiene is a trimer of cyclopentadiene and is easily be formed by heating dicyclopentadiene at a temperature of at least 100xc2x0 C. This compound has two isomers which are, respectively, called 4.9,5.8-dimethano-3a,4,4a,5,8,8a,9,9a-octahydro-1H-benzoindene(I) and 1.4,5.8-dimethano-1,4,4a,4b,5,8,8a,9a-octahydro-9H-fluorene (II). Usually, the ratio of (I) to (II) is 95/5 to 75/25 (weight ratio). In the present invention, such a mixture may be used without any particular problem.
Further, the cyclic olefin (M3) to be used in the present invention, is a compound of the formula [2]: 
wherein each of R1 to R12 is a substituent selected from the group consisting of a hydrogen atom, a halogen atom and a hydrocarbon group having 1 to 20 carbon atoms, provided that R5 and R7 may form a ring together with the carbon atoms, to which they are respectively bonded, and q is an integer of at least 0.
Specific examples of the cyclic olefin (M3) include 2-norbornene, 1,4,5,8-dimethano-1,2,3,4,4a,5,8,8a-octahydronaphthalene, 5-methyl-2-norbornene, 5-ethyl-2-norbornene, 5-propyl-2-norbornene, 5-phenyl-2-norbornene, 5-benzyl-2-norbornene, 5-ethylidene-2-norbornene, 5-vinyl-2-norbornene, 5-chloro-2-norbornene, 5-fluoro-2-norbornene, 5-chloromethyl-2-norbornene, 5-methoxy-2-norbornene, 7-methyl-2-norbornene, 5-isobutyl-2-norbornene, 5,6-dimethyl-2-norbornene, 5,5-dichloro-2-norbornene, 5,5,6-trimethyl-2-norbornene, 5,5,6-trifluoro-6-trifluoromethylnorbornene, 2-methyl-1,4,5,8-dimethano-1,2,3,4,4a,5,8,8a-octahydronaphthalene, 2-ethyl-1,4,5,8-dimethano-1,2,3,4,4a,5,8,8a-octahydronaphthalene and 2,3-dimethyl-1,4,5,8-dimethano-1,2,3,4,4a,5,8,8a-octahydronaphthalene.
Among them, a particularly preferred cyclic olefin (M3) is 2-norbornene or 1,4,5,8-dimethano-1,2,3,4,4a,5,8,8a-octahydronaphthalene.
One constituting component of the catalyst to be used in the present invention, is a metallocene compound (A) which is represented by the formula [1]:
H2C (Rxe2x80x2mCp) (Rxe2x80x3nCp)MX2xe2x80x83xe2x80x83[1]
In the formula, M is zirconium or hafnium, Cp is a group having a cyclopentadienyl skeleton, each of Rxe2x80x2 and Rxe2x80x3 is a hydrocarbon group having 1 to 10 carbon atoms, each of two X""s which may be the same or different from each other, is a halogen atom, a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogenated hydrocarbon group, an alkylamino group, an alkoxy group, an aryloxy group of the formula xe2x80x94Oxe2x80x94Arxe2x80x94Yp (wherein Ar is an aromatic ring, Y is a halogen atom, a hydrogen atom, a hydrocarbon group having 1 to 20 carbon atoms, a halogenated hydrocarbon group, an alkoxy group, an alkylamino group, a cyano group or a nitro group, and p is an integer of from 1 to 5), a thioalkyl group, or a thioaryl group represented by the formula xe2x80x94Sxe2x80x94Arxe2x80x94Yp (wherein Ar, Y and p are as defined above), and each of m and n is an integer of from 0 to 4, provided that m and n are not equal, and m+n is an integer of from 3 to 6.
In the above formula [1], when each of Rxe2x80x2 and Rxe2x80x3 is a hydrocarbon group having 1 to 10 carbon atoms, it may specifically be, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a hexyl group, an octyl group, a 2-ethylhexyl group or a decyl group. Preferred is a hydrocarbon group having 1 to 6 carbon atoms, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group or a hexyl group.
In the above formula [1], when substituent X or substituent Y is a halogen atom, its specific examples include fluorine, chlorine, bromine and iodine.
When substituent X or substituent Y is a hydrocarbon group having 1 to 20 carbon atoms, it may specifically be, for example, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, an octyl group or a decyl group; a cycloalkyl group such as a cyclohexyl group or a cyclooctyl group; an aryl group such as a phenyl group or a naphthyl group; an alkenyl group such as a vinyl group or a propenyl group; an alkenyl group such as an ethynyl group or a propynyl group; an aryl alkyl group such as a benzyl group or a phenetyl group; an aryl alkenyl group such as a styryl group or cinnamyl group; or an alkyl aryl group such as a tolyl group, a xylyl group or a mesyl group.
When substituent X or substituent Y is a halogenated hydrocarbon group, it may specifically be, for example, a chloromethyl group, a fluoromethyl group, a bromomethyl group, an iodomethyl group, a dichloromethyl group, a difluoromethyl group, a trichloromethyl group, a trifluoromethyl group, or a chlorophenyl group.
When substituent X or substituent Y is an alkylamino group, it may specifically be, for example, an N-methylamino group, an anilino group, an N,N-dimethylamino group, an N,N-diethylamino group or an N,N-diphenylamino group.
When substituent X or substituent Y is an alkoxy group, it may specifically be, for example, a methoxy group, an ethoxy group, a propoxy group or a butoxy group.
When substituent X is an alkylthio group, it may specifically be, for example, a methylthio group, an ethylthio group, a propylthio group or a butylthio group.
Further, when substituent X in the formula [1] is a xe2x80x94Oxe2x80x94Arxe2x80x94Y group, it may specifically be, for example, 2-fluorophenoxy, 3-fluorophenoxy, 4-fluorophenoxy, 2-chlorophenoxy, 3-chlorophenoxy, 4-chlorophenoxy, 2-bromophenoxy, 3-bromophenoxy, 4-bromophenoxy, 2-iodophenoxy, 3-iodophenoxy, 4-iodophenoxy, 2,3-difluorophenoxy, 2,4-difluorophenoxy, 2,5-difluorophenoxy, 2,6-difluorophenoxy, 3,4-difluorophenoxy, 3,5-difluorophenoxy, 2,3-dichlorophenoxy, 2,4-dichlorophenoxy, 2,5-dichlorophenoxy, 2,6-dichlorophenoxy, 3,4-dichlorophenoxy, 3,5-dichlorophenoxy, 2,3,4-trifluorophenoxy, 2,3,5-trifluorophenoxy, 2,3,6-trifluorophenoxy, 2,4,5-trifluorophenoxy, 2,4,6-trifluorophenoxy, 3,4,5-trifluorophenoxy, 2,3,5,6-tetrafluorophenoxy, pentafluorophenoxy, 2-fluoromethylphenoxy, 3-fluoromethylphenoxy, 4-fluoromethylphenoxy, 2-chloromethylphenoxy, 3-chloromethylphenoxy, 4-chloromethylphenoxy, 2-trifluoromethylphenoxy, 3-trifluoromethylphenoxy, 4-trifluoromethylphenoxy, 3,5-bis(trifluoromethyl)phenoxy, 2-(2,2,2-trifluoroethyl)phenoxy, 3-(2,2,2-trifluoroethyl)phenoxy, 4-(2,2,2-trifluoroethyl)phenoxy, 2-trichloromethylphenoxy, 3-trichloromethylphenoxy, 4-trichloromethylphenoxy, 2-methylphenoxy, 3-methylphenoxy, 4-methylphenoxy, 2,3-dimethylphenoxy, 2,4-dimethylphenoxy 2,5-dimethylphenoxy, 2,6-dimethylphenoxy, 3,4-dimethylphenoxy, 3,5-dimethylphenoxy, 2,3,4-trimethylphenoxy, 2,3,5-trimethylphenoxy, 2,3,6-trimethylphenoxy, 2,4,5-trimethylphenoxy, 2,4,6-trimethylphenoxy, 3,4,5-trimethylphenoxy, pentamethylphenoxy, 2-methyl-4-fluorophenoxy, 2-chloro-4-fluorophenoxy, 2-chloro-4-trifluoromethylphenoxy, 2-fluoro-4-trifluoromethylphenoxy, 2-trifluoromethyl-4-fluorophenoxy, 2-ethylphenoxy, 3-ethylphenoxy, 4-ethylphenoxy, 2-isopropylphenoxy, 3-isopropylphenoxy, 4-isopropylphenoxy, 2-tert-butylphenoxy, 3-tert-butylphenoxy, 4-tert-butylphenoxy, 3,5-di-tert-butylphenoxy, 2-cyclohexylphenoxy, 3-cyclohexylphenoxy, 4-cyclohexylphenoxy, 1-naphthoxy, 2-naphthoxy, 8-trifluoromethyl-1-naphthoxy, 2,8-dimethyl-1-naphthoxy, 1-tert-butyl-2-naphthoxy, 8-bromo-2-naphthoxy, 2-phenylphenoxy, 3-phenylphenoxy, 4-phenylphenoxy, 2-benzylphenoxy, 3-benzylphenoxy, 4-benzylphenoxy, 2-tolylphenoxy, 3-tolylphenoxy, 4-tolylphenoxy, 2-vinylphenoxy, 3-vinylphenoxy, 4-vinylphenoxy, 2-(2-propenyl)phenoxy, 3-(2-propenyl)phenoxy, 4-(2-propenyl)phenoxy, 2-methyl-6-(2-propenyl)phenoxy, 2-ethynylphenoxy, 3-ethynylphenoxy, 4-ethynylphenoxy, 2-methoxyphenoxy, 3-methoxyphenoxy, 4-methoxyphenoxy, 2-tert-butoxyphenoxy, 3-tert-butoxyphenoxy, 4-tert-butoxyphenoxy, 2-phenoxyphenoxy, 3-phenoxyphenoxy, 4-phenoxyphenoxy, 2-formylphenoxy, 3-formylphenoxy, 4-formylphenoxy, 2-acetylphenoxy, 3-acetylphenoxy, 4-acetylphenoxy, 2-benzoylphenoxy, 3-benzoylphenoxy, 4-benzoylphenoxy, 2-cyanophenoxy, 3-cyanophenoxy, 4-cyanophenoxy, 2-nitrophenoxy, 3-nitrophenoxy, 4-nitrophenoxy, 2-anilinophenoxy, 3-anilinophenoxy, 4-anilinophenoxy, 2-dimethylaminophenoxy, 3-dimethylaminophenoxy, 4-dimethylaminophenoxy, 2-dimethylaminomethylphenoxy, 3-dimethylaminomethylphenoxy or 4-dimethylaminomethylphenoxy.
Further, when substituent X is a xe2x80x94Sxe2x80x94Arxe2x80x94Y group, it may specifically be, for example, 2-methylthiophenoxy, 3-methylthiophenoxy, 4-methylthiophenoxy, 2-tert-butylthiophenoxy, 3-tert-butylthiophenoxy, 4-tert-butylthiophenoxy, 2-fluorothiophenoxy, 3-fluorothiophenoxy, 4-fluorothiophenoxy, 2-chlorothiophenoxy, 3-chlorothiophenoxy, 4-chlorothiophenoxy, 2-trifluoromethylthiophenoxy, 3-trifluoromethylthiophenoxy, 4-trifluoromethylthiophenoxy, 2-methoxythiophenoxy, 3-methoxythiophenoxy, 4-methoxythiophenoxy, 2-cyanothiophenoxy, 3-cyanothiophenoxy, 4-cyanothiophenoxy, 2-nitrothiophenoxy, 3-nitrothiophenoxy, 4-nitrothiophenoxy, 2-anilinothiophenoxy, 3-anilinothiophenoxy, 4-anilinothiophenoxy, 2-dimethylaminothiophenoxy, 3-dimethylaminothiophenoxy, 4-dimethylaminothiophenoxy, 2-dimethylaminomethylthiophenoxy, 3-dimethylaminomethylthiophenoxy or 4-dimethylaminomethylthiophenoxy.
Specific examples of the metallocene compound (A) of the formula [1] include methylene(cyclopentadienyl)(tetramethylcyclopentadienyl) zirconium dichloride, methylene(2-methylcyclopentadienyl) (tetramethylcyclopentadienyl) zirconium dichloride, methylene(3-methylcyclopentadienyl) (tetramethylcyclopentadienyl)zirconium dichloride, methylene(cyclopentadienyl)(2,3,5-trimethylcyclopentadienyl)zirconium dichloride, methylene(cyclopentadienyl)(2,3,4-trimethylcyclopentadienyl)zirconium dichloride, methylene(2-methylcyclopentadienyl)(2,3,4-trimethylcyclopentadienyl)zirconium dichloride, methylene(3-methylcyclopentadienyl)(2,3,5-trimethylcyclopentadienyl)zirconium dichloride, methylene(2-methylcyclopentadienyl)(2,3-dimethylcyclopentadienyl)zirconium dichloride, methylene(3-methylcyclopentadienyl)(2,4-dimethylcyclopentadienyl)zirconium dichloride, methylene(2-methylcyclopentadienyl)(2,5-dimethylcyclopentadienyl)zirconium dichloride, methylene(2-methylcyclopentadienyl)(2,3,5-trimethylcyclopentadienyl)zirconium dichloride, methylene(3-methylcyclopentadienyl)(2,3,4-trimethylcyclopentadienyl)zirconium dichloride, methylene(2-methylcyclopentadienyl)(2,4-dimethylcyclopentadienyl)zirconium dichloride, methylene(2-methylcyclopentadienyl)(3,4-dimethylcyclopentadienyl)zirconium dichloride, methylene(3-methylcyclopentadienyl)(2,3-dimethylcyclopentadienyl)zirconium dichloride, methylene(3-methylcyclopentadienyl)(2,5-dimethylcyclopentadienyl)zirconium dichloride, methylene(3-methylcyclopentadienyl)(3,4-dimethylcyclopentadienyl)zirconium dichloride, methylene(2,3-dimethylcyclopentadienyl)(2,3,5-trimethylcyclopentadienyl)zirconium dichloride, methylene(2,4-dimethylcyclopentadienyl)(2,3,5-trimethylcyclopentadienyl)zirconium dichloride, methylene(2,3-dimethylcyclopentadienyl)(2,3,4-trimethylcyclopentadienyl)zirconium dichloride, methylene(2,3-dimethylcyclopentadienyl) (tetramethylcyclopentadienyl)zirconium dichloride, methylene(2,4-dimethylcyclopentadienyl) (tetramethylcyclopentadienyl)zirconium dichloride, methylene(2,5-dimethylcyclopentadienyl) (tetramethylcyclopentadienyl)zirconium dichloride, methylene(3,4-dimethylcyclopentadienyl) (tetramethylcyclopentadienyl)zirconium dichloride, methylene(2,4-dimethylcyclopentadienyl)(2,3,4-trimethylcyclopentadienyl)zirconium dichloride, methylene(2,5-dimethylcyclopentadienyl)(2,3,4-trimethylcyclopentadienyl)zirconium dichloride, methylene(2,5-dimethylcyclopentadienyl)(2,3,5-trimethylcyclopentadienyl)zirconium dichloride, methylene(3,4-dimethylcyclopentadienyl)(2,3,4-trimethylcyclopentadienyl)zirconium dichloride, methylene(3,4-dimethylcyclopentadienyl)(2,3,5-trimethylcyclopentadienyl)zirconium dichloride, methylene(3-ethylcyclopentadienyl) (tetramethylcyclopentadienyl)zirconium dichloride, methylene(cyclopentadienyl)(tetramethylcyclopentadienyl) bis(2-fluorophenoxy)zirconium, methylene(3-methylcyclopentadienyl)(tetramethylcyclopentadienyl)bis(2 -fluorophenoxy)zirconium, methylene(cyclopentadienyl)(tetramethylcyclopentadienyl) zirconium dimethyl, methylene(cyclopentadienyl)(tetramethylcyclopentadienyl) zirconium diphenyl, methylene(cyclopentadienyl)(tetramethylcyclopentadienyl) bis(2-trifluoromethylphenoxy)zirconium, methylene(cyclopentadienyl)(tetramethylcyclopentadienyl) bis (2-methyl, 4-fluorophenoxy) zirconium, methylene(cyclopentadienyl)(tetramethylcyclopentadienyl) zirconium dimethoxide, methylene(cyclopentadienyl)(tetramethylcyclopentadienyl) zirconium diphenoxide, methylene(3-methylcyclopentadienyl)(tetramethylcyclopentadienyl) zirconium dithiophenoxide, methylene(3-methylcyclopentadienyl)(tetramethylcyclopentadienyl)bis(4-cyanophenoxy)zirconium, and methylene(2-n-butylcyclopentadienyl)(tetramethylcyclopentadienyl)bis(2-trifluoromethylphenoxy)zirconium.
Furthermore, the corresponding hafnium compounds having the transition metal atoms in the above-mentioned compounds changed from zirconium to hafnium, may likewise be used.
The aluminoxane (B) as another component constituting the catalyst to be used in the method of the present invention, is presented by the following formula [3]: 
In the formula, R13 is an alkyl group having 1 to 8 carbon atoms, and r is a number of from 4 to 100.
R13 may specifically be, for example, a methyl group, an ethyl group, a propyl group, an isobutyl group or a combination thereof. A preferred aluminoxane is an aluminoxane of the formula [3] wherein all or the majority of R1 is a methyl group, i.e. a methylaluminoxane. Such an aluminoxane (B) usually has a molecular weight of from 200 to 10,000, and its structure may be of a linear structure, or a compound wherein both terminals are bonded to form a ring, may also be used.
Various known methods may be used for the synthesis of the aluminoxane (B). For example, it can be synthesized by a method wherein a trialkylaluminum is dissolved in a hydrocarbon solvent, and water in an equivalent amount to the trialkylaluminum is gradually added to the solution for hydrolysis, a method wherein copper sulfate hydrate or aluminum sulfate hydrate is suspended in a hydrocarbon solvent and contacted with a trialkylaluminum in an amount of from 1 to 3 equivalents to the hydrate crystal water in this suspension to slowly hydrolyze the trialkylaluminum, or a method wherein a trialkylaluminum in an amount of from 1 to 3 equivalent is contacted to adsorbed water of non-dehydrated silica gel suspended in a hydrocarbon solvent to slowly hydrolyze the trialkylaluminum.
The above catalyst components (A) and (B) may be used as they are, but they may be supported on a carrier, as the case requires. As such a carrier, an inorganic compound such as silica, alumina or magnesium chloride, or an organic polymer compound such as polyethylene or polypropylene, may, for example, be mentioned.
Copolymerization of ethylene (M1) with dicyclopentadiene or tricyclopentadiene (M2), or copolymerization of (M1) and (M2) and a cyclic olefin (M3) incorporated as the case requires, in the method of the present invention, is induced by the above-mentioned catalyst comprising the metallocene compound (A) and the aluminoxane (B). This catalyst is usually formed by contacting the two components. An optional method may be employed as a method of contacting them. Namely, the metallocene compound (A) and the aluminoxane (B) may be preliminarily mixed in a suitable solvent, and they may be supplied to the polymerization system in the form of a solution. Otherwise, the metallocene compound (A) and the aluminoxane (B), or their solutions in monomers or in suitable solvents, may be supplied to the polymerization system simultaneously or separately to let them contact in the polymerization system.
The amount of the metallocene compound (A) to be used in the copolymerization of the present invention, is usually within a range of from 10xe2x88x926 to 1 g atom/l, preferably from 10xe2x88x925 to 10xe2x88x921 g atom/l, as the concentration of the transition metal in the polymerization reaction system. Further, the amount of the aluminoxane (B) is usually within a range of from 10xe2x88x924 to 10 g atom/l, preferably from 10xe2x88x923 to 1 g atom/l, as the concentration of aluminum atoms in the polymerization reaction system. The ratio of the aluminoxane (B) to the metallocene compound (A) in the polymerization reaction system is usually within a range of from 1 to 107, preferably from 10 to 105, as the ratio of aluminum atoms in the aluminoxane (B) per mol of the metallocene compound (A).
For the polymerization in the present invention, any polymerization method may be employed such as a gas phase polymerization method, a bulk polymerization method, or a solution or slurry polymerization method employing a suitable solvent. These methods may be batch-wise or continuous. In a case where a solvent is used, an inert hydrocarbon solvent is usually employed, but dicyclopentadiene, tricyclopentadiene or a cyclic olefin itself, which is a monomer to be used for the polymerization, may be used as the solvent. As the inert hydrocarbon solvent, an aliphatic hydrocarbon such as butane, isobutane, pentane, hexane, octane or decalin; an alicyclic hydrocarbon such as cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane or dimethylcyclohexane; an aromatic hydrocarbon such as benzene, toluene or xylene; or a petroleum fraction such as naphtha, kerosine oil or light oil, may, for example, be used.
With respect to the polymerization conditions of the present invention, the temperature is usually from xe2x88x92100 to 250xc2x0 C., preferably from xe2x88x9250 to 200xc2x0 C., and the pressure is usually at most 10 MPa, preferably from atmospheric pressure to 5 MPa.
In the cyclic structure-containing copolymer obtained by the method of the present invention, units derived from ethylene (Ml) are within a range of from 5 to 99 mol %, preferably from 15 to 95 mol %, particularly preferably from 30 to 90 mol %, units derived from dicyclopentadiene or tricyclopentadiene (M2) are within a range of from 1 to 95 mol %, preferably from 5 to 85 mol %, particularly preferably from 10 to 70 mol %, and units derived from a cyclic olefin (M3) are within a range of from 0 to 90 mol %, preferably from 0 to 80 mol %, particularly preferably from 0 to 70 mol %. The units derived from ethylene (M1), the units derived from dicyclopentadiene or tricyclopentadiene (M2) and the units derived from a cyclic olefin (M3) are randomly arranged to form a substantially linear olefin type random copolymer. The fact that the cyclic structure-containing copolymer of the present invention is substantially linear and has no gelled crosslinking structure, can be ascertained by the fact that the obtained copolymer dissolves completely in decalin at 135xc2x0 C.
Further, the molecular weight of the cyclic structure-containing copolymer of the present invention is such that the weight average molecular weight Mw measured by gel permeation chromatography (GPC) is usually within a range of from 500 to 2,000,000, particularly from 1,000 to 1,000,000, and the number average molecular weight Mn is from 300 to 1,000,000, particularly preferably from 500 to 500,000. Here, the Mw/Mn value as an index of the molecular weight distribution is usually from 1.5 to 4.5. If the Mw/Mn value exceeds 4.5, and when the cyclic olefin type copolymer of the present invention is to be used for an optical material after being modified chemically, the mechanical strength tends to deteriorate, and a uniform molded product can hardly be obtainable. The cyclic structure-containing copolymer of the present invention has a narrow molecular weight distribution, and a uniform distribution of the monomer composition, whereby it is excellent in heat resistance and mechanical properties.
The cyclic structure-containing copolymer of the present invention may be used as it is, but since it contains an olefinic double bond, a chemical modification such as epoxidation, oxidation, chlorination or bromination may be carried out by utilizing such a double bond, to let it have properties more suitable for various applications, before use. With respect to specific applications, a low molecular weight product is useful in the fields of e.g. a toner for electrostatic copying, a hot-melt adhesive, a ceramic binder and a photoresist substrate, and a high molecular weight product is useful in various fields such as an optical field of e.g. an optical lens, an optical disk or an optical fiber, an electric field of e.g. an electric oven, a liquid crystal display substrate, a printed circuit board or a transparent electroconductive film and a medical and chemical field of e.g. an injection syringe, a pipette or an animal gauge.
Now, the present invention will be described in further detail with reference to Examples. However, it should be understood that the present invention is by no means restricted to such specific Examples.
In the Examples, the copolymer composition (mol %) was obtained by 13C-NMR spectroscopy (100 MHz, temperature: room temperature, solvent: deuterated benzene), and the weight average molecular weight (Mw), the number average molecular weight (Mn) and the molecular weight distribution (Mw/Mn) were obtained by the measurements by a high temperature gel permeation chromatography (GPC) under such conditions that the temperature was 135xc2x0 C. and the solvent was 1,2,4-trichlorobenzene. Further, the reactions for the syntheses of metallocene compounds in the Reference Examples were all carried out in an inert gas atmosphere, and the reaction solvent used, was preliminarily dried.